1. Field of the Invention
The present disclosure relates to an X-ray detector, and more particularly, to an X-ray detector for an X-ray signal to output the X-ray signal as a digital signal.
2. Discussion of Related Art
An X-ray detector is a device for detecting an X-ray signal to convert the detected X-ray signal into an electrical signal, and generally converts an X-ray signal into an electrical signal using a photodiode.
In other words, a scintillator or a phosphor being located in front of a photodiode may absorb X-rays to radiate visible light corresponding to the absorbed X-rays, the photodiode may convert the visible light into a photocurrent in proportion to an amount of the visible light, and the converted photocurrent may be measured to detect the X-rays.
Such a photodiode generally detects light using a PN junction of a semiconductor. That is, the photodiode detects light using a phenomenon in which electrons and holes of a positive charge are generated when light is incident to cause a current to flow.
As a photodiode, a PIN diode, an avalanche photodiode (APD) and the like are mainly used. A PIN photodiode has a structure in which an intrinsic semiconductor layer having a large resistance due to a small carrier is disposed in the middle of a PN junction.
On the other hand, an APD photodiode has an avalanche layer in the middle of a PN junction and a carrier generated according to excitation of incident light collides with an atom in the avalanche layer by a high electric field to newly generate a hole-electron pair.
And, the APD photodiode uses the principle that an avalanche effect is generated in the collision process of such hole-electron pairs to increase a photocurrent.
Meanwhile, the background art of the present disclosure is disclosed in Korean Laid-Open Patent Application No. 10-2014-0087247 (Jul. 9, 2014).